Electric motors and generators have many applications. In a typical motor or generator, there is a rotor that rotates within a stator. The stator includes a plurality of fingers that define rotor slots therebetween. Wires are wound around the fingers and through rotor slots to define coils. Each coil must be insulated for proper operation. Insulation, in the form of slot wedges, is inserted into the stator slots to insulate coils from the stator.
It is common to create slot wedges from a strip of insulation that is unwound from a roll. Rolled strips are typically created by (i) unwinding a web of sheet-like insulation from a roll, (ii) passing the web between rolling scissors/knives to cut the web into strips of insulation, and (iii) rolling the strips into individual rolls. Then, as a separate step, a rolled strip of insulation is supplied to a machine that insulates stators. That machine (i) unwinds the strip from its roll, (ii) cuts the strip into "short" lengths, and (iii) inserts the short lengths into stator slots. The short lengths are inserted prior to the installation of the coils onto the stator. During the process of inserting the short lengths, they become somewhat U-shaped in an end profile view. Examples of machines that insert slot wedges or insulating slot cuffs into stator slots are disclosed in U.S. Pat. Nos. 2,340,291; 3,616,512; 3,831,255; 3,778,889; 3,778,890; 4,831,716; 4,878,292; 4,854,033; and Re. 34,195.
A common manufacturing defect associated with stators has to do with the insulation of stator slots. If a stator slot is not properly insulated, the coil therein electrically shorts/fails. While prior methods and apparatus for insulating stator slots are generally effective, these type of manufacturing defects still occur, and they typically render motors and generators inoperative. Unfortunately, such defects are often not detected until stators are completely assembled. It is typically cost prohibitive to remanufacture a defective stator; therefore, such defects result in considerable waste and expense. Even worse, such defects are often not detected until after electric motors and generators are placed into service.
Accordingly, there is a need for improved methods, apparatus, and articles of manufacture for forming slot wedges to decrease manufacturing defects in stators.